Don't know about turbos of any manufacture, but the wide open throttle limitation of cruise control was the same on any other car I can recall. I used to travel and rent a lot-- sometimes they'd give me luxury cars I guess to save the sensible ones for the less frequent renters. I think I was being picky because a friend had a 64 New Yorker that used a complicated servo motor with magnetic clutch instead of the usual vacuum servo. He judged its ability to keep a set speed within parts of a mile-per-hour.

Only reason I ever set the cruise is to see if it does a better job at economy than my foot does. Don't think it makes much difference.

I've been keeping my eye out for the 12V vacuum pump that comes on the 90's cars with cruise. Next time I see one in the boneyard... I was thinking it would be cute to see the cruise have the strength to downshift up the long grades.

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Art Benstein near Baltimore